This relates generally to imaging devices, and more particularly, to imaging devices having power supply noise rejection capabilities.
Image sensors are commonly used in electronic devices such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an electronic device is provided with an array of image pixels arranged in pixel rows and pixel columns. Circuitry is commonly coupled to each pixel column for reading out analog image signals from the image pixels. Power supplies (e.g., voltage sources) are used to provide a power supply voltage to image pixels to drive any relevant circuitry.
A regulator circuit can be used to distribute and provide power to image pixels, but such a configuration with a single regulator circuit can require a high input supply voltage, which is not desired. A booster circuit can be used in combination with the regulator circuit to reduce the input supply voltage. However, there is a tradeoff between the booster circuit's ability to provide an incremental amount of power (e.g., to supply a corresponding voltage) and output noise. In other words, when the booster circuit generates a high voltage, the high voltage usually includes a large noise component.
Because the output noise of the booster circuit propagates through the circuitry within the image pixels, the power supply noise corresponds to the output noise of the booster circuit. To meet the power demands of the image pixels, a large amount of power supply noise is produced by the booster circuit. The power supply noise produced by the regulator and booster circuit combination and supplied to the image pixels are detrimental to the operations of the image sensor.
It would therefore be desirable to be able to provide imaging devices with power supply noise rejection capabilities.